Solenoid valves are used to control a flow of fluid (e.g., air, liquid or gas) within a system such as an air conditioning, hydraulic brake, or fuel system. A solenoid valve opens and closes flow passages by energizing a coil to produce a magnetic field which in turn, moves an internal armature.
A pressure sensor or transducer is used to monitor fluid pressure within a system, such as a pneumatic or hydraulic system. As used herein, a pressure transducer includes both a pressure transducer and a pressure sensor. Generally, the measured pressure information is provided to an electrical control unit (ECU) located externally to a solenoid valve and which activates or deactivates (opens or closes) the solenoid valve based on the pressure information. There are several types of technology employed for pressure sensors and transducers which include, but are not limited to, ceramic, resistive, linear variable differential transformer (LVDT), piezoresistive, and piezoelectric. One common form of sensing pressure in automotive applications utilizes capacitive type sensors; however, these sensors require large volumes of space to house the sensing element and electronics.
In an effort to improve efficiencies, reduce costs, and miniaturize package size, system designers often try to eliminate components while still maintaining the same or an improved level of performance. In conventional systems, a discrete pressure sensor can be added to an existing solenoid valve body or housing. However, in such a system, the overall packaging of the combination device is quite large and does not integrate them into one unit. Also, combining two or more devices does not eliminate leak paths in the system.
A solenoid valve and a pressure transducer can be used to monitor and control the same types of fluid pressure; combining these two discrete components into one device would add value to a system. What is needed is an integrated solenoid pressure transducer that will provide an efficient method of incorporating pressure-sensing technology within an original envelope (housing) of a solenoid valve, and preferably provide a common electrical connection point. In addition, the integrated solenoid pressure transducer should preferably be easy and inexpensive to manufacture based on structural simplicity and the use of inexpensive materials.